nsogiba

Just wanted to share my current project with the group...

I love the idea of exhaust cutouts. Loud when you want it, civilized to keep yourself, the wife, and neighbors happy. My electric QTP on my old 6.0 BMW just didn't stand up to the year round elements, the motor crapped out after about 6 months. This was in 2011. Vendor told me I couldn't replace any parts, so it's been sitting in the basement ever since. I wanted to try something different, with less moving parts, less to go wrong, little to no wiring, no electric motors, etc. They also have the added benefit of being a bit smaller than electric units with no bulky motor sticking out to the side, which can sometimes make packaging the system difficult in tight applications.

I purchased valves that are normally closed. The NPP cutouts on all the newfangled GM stuff are normally open, and as soon as a vacuum is applied, they slam shut. Nothing wrong with this, but it means they're open on cold start, and when vacuum builds a few seconds later, they shut. I'm not sure if GM gets around this by using a vacuum canister. I did not want this situation since I leave for work early in the morning and wanted to maintain some sanity for my neighbors. I could have gotten around this by using a check valve and a vacuum canister but that's added complexity, and I have no idea if the vacuum canister would hold a charge for sitting a week at a time (which is a reality if we have a couple days of nasty weather). The last item that turned me off from the normally open was that in the event of any vacuum fitting/line failure the valves would fail open, and I'd have to drive around with the car stupidly loud until I got it fixed. I would much rather they fail in the normally closed position.

Vacuum actuated, normally closed. 3". I am using V-bands so that I can remove the cutout for service if need be without having to remove the whole pipe. Fishmouthed a 3" piece of stainless so I can saddle the whole thing on my XS Power midpipes (right around the trans area).










Jury is still out on whether these will be any better than the electric ones. The actuators could fail, linkage could get sticky, valve could leak exhaust when closed, but so far they look to be of initially good quality. Time will tell. But, if the OEMs are using them (NPP option on GM performance cars, BMW has used them for some time as well), the principle makes sense over electrical.

I will need to put some kind of turn down together for the outlet of the valve, possibly wrap the leaf spring in heat resistant insulation to prevent melting it. I might do the gold insulating wrap or fab up some kind of sheetmetal deflector.

A vacuum solenoid, controlled by a toggle switch, will decide if the cutout sees vacuum or not. That part is easy. The harder part is actually having vacuum available to the solenoid. Under WOT vacuum goes away, so unless you have a vacuum check valve installed the vacuum will go away and cutout will close. Luckily OEMs have been using vacuum to power things forever so we have a reliable inexpensive solution available off the shelf.


So let's say you're done tooling around with the valves open and want to shut them because your ears are bleeding, you remove power from the solenoid (again via toggle switch), but the valves stay open, because the check valve is still holding the existing vacuum to the valves. This is where I am on the fence, I could install a momentary pushbutton bleeder valve; either way that portion of the lines needs to be bled of vaccum in order for the valves to shut.


For the record this is going on a 2000 FRC with basic bolt ons. LS6 intake, zip tie mod, XS Power longtubes, 3" catless X-pipe, and Z06 Titanium mufflers.

Greg_E

Nice work!
You could use an ON-OFF-MOMENTARY ON switch wired to a vacuum dump solenoid valve. That way you don't have to deal with two separate switches. Do a search for Contura bilge pump switch. It might fit the bill.

Make sure you post pictures or a video (even better) when it's all finished.

StuntHeavy

Very cool. I love to see one-off, quality mods like this. It's nice to see someone make it their own.

I worked for BMW when they were using the vacuum actuators on everything. Much like their turbo wastegates, their exhaust actuators would rattle their gibblets off. If you ever hear a 335i on cold start, usually one or the other is rattling. Your parts look to be of much better quality though.

Looking forward to seeing how this turns out!

nsogiba

Thanks, guys. I am looking for a 3-way vacuum solenoid (12V) right now that dumps when switched. Might try out one from a Mazda application, we will see. Have to stop by the junkyard this weekend.

Stroker87

nsogiba

got the fishmouths mocked up on the midpipes, traced out the insides, removed the pipes from the car. drove around the block with no pipes, wow it's loud, should be fun. also tacked together fishmouths to v-bands, v-bands to valves. I forgot to order turndowns so I don't melt anything, got a 180* mandrel bend on the way from summit, will be here in a couple days.

_DSC4955 by Norbert Ogiba, on Flickr

_DSC4957 by Norbert Ogiba, on Flickr

_DSC4958 by Norbert Ogiba, on Flickr

CaseyJones

I'm surprised someone hasn't tried a bypass setup that uses one of the factory tailpipes as a bypassed exhaust and the other as a muffled one. As on a Z06, the muffler is one in and one out with the tailpipes split off the single outlet. Why not try removing the innermost exhaust outlet, configure the bypass to tap off the midpipe just upstream of the muffler and then route out where the original inner tailpipe exit was? It would look factory from the back and safely allow exhaust out the rear. That would look good and sound good without dumping under the car.

nsogiba

great idea. it might be tough packaging all that in the fairly small space between the outlets but wouldn't be impossible. I think it's out of reach for a lot of folks because of the titanium construction of the Z06 exhaust. regular steel C5 exhaust, no problem. If I wasn't running a titanium exhaust, I would have done this option as it basically eliminates the drone that occurs with cutouts open

carluver

I recently did this mod to a set of stock pipes i bought off c list ,I removed inside two tail pipes from the mufflers and welded them shut with a 1 1/4" fender washer, then with a 2 5/8" holesaw drill one hole in each rear most bend in the prrimary pipe and weld on the 2.5 " normally open vacuum cutout, next i welded 2.5" pipe from cutout to a 1" piece of the oval tip, then add stock chrome tip, next i ran the vacuum line to passenger side of the manifold after the throttle body. this settup is very quiet [quieter then my buick] during part throttle due to one of the tailpipes being welded shut and opens at just the right time about 1/2 throttle leaving you with open exhaust I also used three vacuum solenoids from the junkyard to run these in closed, auto, or open mode. I personally think this is the best exhaust i have ever heard on a c5. If i knew how to post pics I have some.

carluver

here are some pics these begin to open at 10" vacuum and are fully open at 5" vacuum so they might not work so well on a cammed car.

CaseyJones

I like it!

nsogiba

very cool! do you have a video of them in action? Must sound great.

nsogiba

my buddy is TIG'ing everything up for me and sent me some pics

image by Norbert Ogiba, on Flickr

image by Norbert Ogiba, on Flickr

image by Norbert Ogiba, on Flickr

image by Norbert Ogiba, on Flickr



Coworker bought an '01 Coupe with a 6 speed, great condition, 60K

image by Norbert Ogiba, on Flickr

then, this
image by Norbert Ogiba, on Flickr

which works out fine because i'm gonna tear it down this week for the valve springs and intake, install exhaust, etc.

carluver

nope no video. i wish my fit and finish would've turned out as nice as yours ,they look great so far.

the gm vacuum solenoids i used came off a 98 3.8 ltr gm grand am it is a vapor canister purge valve, itholds tight in one direction and bleeds slowly in the other direction when no power applied [normally closed] so it acts like a check valve. easy to grab they are right up front on the left side of front valve cover i found the vacuum only holds in one direction though so it took some experimenting and they will hold them shut for as much as three days, maybe longer. i started out with one and then ended up useing a series of three solenoids so i could lock them shut leave them open or let them open and close based on engine vacuum.

lionelhutz

FYI, the C5 already has a vacuum storage canister. It's located on the right of the firewall just ahead of the passenger side door hinges. It provides the vacuum to run the air doors in the HVAC which direct the air to the proper vents.

You can easily find 3-port EGR vacuum solenoids that will dump the vacuum when powered-off.

nsogiba

^ any recommendations on where to find a 3-port solenoid that will do what I need? Would be great if it were off a common application so I could source it easily.

lionelhutz

A Google Image search showed this picture in the first row.

http://www.fullsizebronco.com/forum/...ml#post5052178

nsogiba

Ok, I had seen a few like that (very common on Ford applications) but wasn't sure if they vented to atmosphere. I will make a trip to the junkyard and grab a few. Looks like they were used in the 2000 era Taurus, tons of those around here.

carluver

all of the three port solenoids i pulled only had a positive seal in one direction, that is why i ended up using three seperate ones, i kind of gave up after trying about 6 or 7 different types from the bone yard,if you do find one i would be interested in the part number so i could clean up my setup.

qwck10th

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Steve C.